forked from cerc-io/ipld-eth-server
98 lines
2.7 KiB
Go
98 lines
2.7 KiB
Go
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// Package attr provides attributes for text and data sections.
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package attr
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import (
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"fmt"
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"math/bits"
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"strings"
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)
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// Attribute represents TEXT or DATA flags.
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type Attribute uint16
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// Reference: https://github.com/golang/go/blob/35f4ec152b44ae5fc83aaf68e2eb3aa1a778e5cd/src/runtime/textflag.h#L11-L34
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//
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// // Don't profile the marked routine. This flag is deprecated.
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// #define NOPROF 1
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// // It is ok for the linker to get multiple of these symbols. It will
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// // pick one of the duplicates to use.
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// #define DUPOK 2
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// // Don't insert stack check preamble.
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// #define NOSPLIT 4
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// // Put this data in a read-only section.
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// #define RODATA 8
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// // This data contains no pointers.
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// #define NOPTR 16
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// // This is a wrapper function and should not count as disabling 'recover'.
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// #define WRAPPER 32
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// // This function uses its incoming context register.
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// #define NEEDCTXT 64
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// // Allocate a word of thread local storage and store the offset from the
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// // thread local base to the thread local storage in this variable.
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// #define TLSBSS 256
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// // Do not insert instructions to allocate a stack frame for this function.
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// // Only valid on functions that declare a frame size of 0.
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// // TODO(mwhudson): only implemented for ppc64x at present.
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// #define NOFRAME 512
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// // Function can call reflect.Type.Method or reflect.Type.MethodByName.
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// #define REFLECTMETHOD 1024
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//
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const (
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NOPROF Attribute = 1 << iota
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DUPOK
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NOSPLIT
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RODATA
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NOPTR
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WRAPPER
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NEEDCTXT
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_
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TLSBSS
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NOFRAME
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REFLECTMETHOD
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)
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// Asm returns a representation of the attributes in assembly syntax. This may use macros from "textflags.h"; see ContainsTextFlags() to determine if this header is required.
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func (a Attribute) Asm() string {
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parts, rest := a.split()
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if len(parts) == 0 || rest != 0 {
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parts = append(parts, fmt.Sprintf("%d", rest))
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}
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return strings.Join(parts, "|")
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}
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// ContainsTextFlags returns whether the Asm() representation requires macros in "textflags.h".
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func (a Attribute) ContainsTextFlags() bool {
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flags, _ := a.split()
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return len(flags) > 0
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}
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// split splits a into known flags and any remaining bits.
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func (a Attribute) split() ([]string, Attribute) {
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var flags []string
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var rest Attribute
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for a != 0 {
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i := uint(bits.TrailingZeros16(uint16(a)))
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bit := Attribute(1) << i
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if flag := attrname[bit]; flag != "" {
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flags = append(flags, flag)
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} else {
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rest |= bit
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}
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a ^= bit
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}
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return flags, rest
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}
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var attrname = map[Attribute]string{
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NOPROF: "NOPROF",
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DUPOK: "DUPOK",
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NOSPLIT: "NOSPLIT",
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RODATA: "RODATA",
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NOPTR: "NOPTR",
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WRAPPER: "WRAPPER",
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NEEDCTXT: "NEEDCTXT",
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TLSBSS: "TLSBSS",
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NOFRAME: "NOFRAME",
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// REFLECTMETHOD excluded due to https://golang.org/issue/29487
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}
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